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Michael Wentland

Interested to see how your research goes. I've always wondered whether skipping intervals all together was a good idea during base. I can't see the harm in 1-2 per week sprinkled in at moderate intensity.

Also, the references at the bottom of the post is why we all look to you for good solid info Joe. Thank you for your professionalism.



thanks Joe. BTW, where does efficiency fit into the equation? Doesn't zone 2/3 work improve your efficiency thus reducing the effort required to perform at a particular speed /pace?And then would training/racing at the lower intensity burn more fat than carbs ?


Hi Joe
I just read Jonas Coltings new book on health. Jonas is a well known triathlete around the world and a "health-guru" in Sweden (were I also live).
He argues that fasting is a good thing, for many reasons:

1) Your insulin levels drops significantly
2) Your energy level becomes steady
3) Fatburning increases (especially when the insulin level is low)
4) weight loss
5) Human growth hormone (hGH) secrete in higher levels. He calls this "human/natural doping"
6) You break a habit of always wanting food (especially sugar).
7) Your digestion get to rest and blood is directed to other parts of your body

He recommend a 24-36 hour fasting every third or fourth week, and that you do a short interval session at the end of the fasting period. He is also pro-paleo.

So my question is if you are as positive to fasting as he is?

Keep up your excellent work and writing!

Joe Friel

Anders--Sounds interesting. I have no experience with it and never seen research that addresses these points. Thanks for your post.

Joe Friel

Neeraj--The more efficiently you move the fewer total calories you burn at any given intensity. And yes, an improvement in efficiency would theoretically increase fat burning. Good point.


As an amature , I can say that one reason for not burning fat so well, is the fear of the bonk. I had one bonk that was a dreadful experience, very close to home, and the world went topsy turvy. For the next 6 months I was drinking those carb loaded sugar loaded vitamin loaded drinks that are aimed at all of us sports types. I realised that even though my training was increasing, so was my weight. It was on a 3 hour ride, when I had 2 litres of sports drink on the bike, and a couple of gels in my back pocket, and bars, that I noticed the lean guy beside me had one tiny bottle. It had watered down grape juice in it. I thought about this. I went home and read. I realised that being 6kg over weight I didn't need to drink 500mls in a hour of swim training when I was getting thirsty. Water fine, even with a big of sugar or an isotonic tablet perhaps but certainly not the full energy replacement drinks. Once I cut back on those, I noticed a significant difference.



According to Mark Allen, he made the leap into Ironman history by dropping the high intensity regime until after he had maxed out his base training (months of workouts at or below his aerobic threshold). Noakes even mentions in his book Lore of Running, that this approach to training is rarely used by many athletes and might also explain how Allen sustained his success for so long.

Chuckie V echoed the same sentiments in his blog about how the body responds to high volume low intensity running (55% max V02). http://chuckiev.blogspot.com/2007/08/hadds-approach-to-distance-training-run.html

From what I've read, the goal of training is to signal to your body the need to build mitochondria, slow twitch fibers, and blood vessels. These components are the basis for improving the conversion of oxygen and fat into ATP. Diet, recovery, age, and genetics all play a part, but they each play a complimentary role to the base which is training. Or perhaps I have it wrong and the order varies based on the individual as some athletes have different genetic limiters and their training must reflect those limiters?

So I guess my question is that the key to becoming a fat burning machine different based on the individual, or is this more of a one shoe fits all process. That despite our genetic variation, all athletes would benefit from "X" style of base training?

Joe Friel

Travis--Some will benefit more from base training--esp those who are new to intermediate level. Highly experienced elite athletes will reap less of a reward.

Dave F

Curious what the "worst ever" athlete's numbers were? My fat burning is also poor. My last test showed RER above .9 and 50/50 %CHO/%FAT at ~66% of VO2 power and uptake (35.8 against a max of 60.2). Being a masters bike racer and 10k runner, this doesn't hurt me so much, but I can't "ride off" weight so easily either. I theorize that I've been too diligent about post-workout glycogen replenishment and thus "trained up" my glycogen stores to very high levels. Since you did not mention post-workout routines as a factor, I thought I'd ask. Thanks!


Why would you suggest training in zones 2 and 3 to improve fat utilization? It seems most studies agree that the most efficient fat burning heart rate is below 75% of VO2 max... wouldn't this be HR zone 1?

Jaakko Mursu

Interesting study about the benefits of training in a fasted stated compared to fed state (eating a meal). Training in a fasted state resulted better ability to use fat during the exercise.

Karen Van Proeyen, Karolina Szlufcik, Henri Nielens, Monique Ramaekers, and Peter Hespel. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol 2011;110 236-245



Joe, Its pretty common knowledge about the "fat burning" zones and most gym trainers go on about it. What my question is, if you are a very low % bodyfat person will training at high/er intensities lead to a loss in muscle mass above and beyond the fat burning amount? If so, what would fueling before and during offset that?

Joe Friel

Cookie--Even the skinniest endurance athlete has plenty of fat to fuel a workout of any duration.


Some points in your outline about fat need clarification, Joe:
Its a myth that the body will slowly adapt to fat burning when deliberately shifting the ratio from carbs to fat. Also its a myth that omega fatty acids such as from fish can be used as a major source of energy in human beings although some dietary experts may want us to believe this.
Instead, what it takes is an abrupt halt to ingesting carbohydrates and a special diet based on certain triglycerides and cholesterols to successfully switch to burning fat without leaving any counter-productive residues such as ketones in your body. For an athlete it is of utmost importance that he goes through a process of 100% sugar/starch deprivation until his body will accept metabolising fat and its by-products efficiently. Once done that its a mighty tool for any sports longer than an hour. Since 1998 I publish and conduct a form of fat diet labelled CREAM DIET many long distance athletes took successful advantage of. That's why I dare to say that no, switching to fat metabolism should exclusively be done under the guidance of a skilled practitioner, a naturopath or someone at least trained well in the field of medicine. Reason? Because many residues of former medication store in our fat tissues Now they come up soon his owner decides to diminish his percentage of body fat. Old symptoms may occur and unless they don't get properly re-treated they may cause unwanted side effects such as Collie referred to in his post which can make fat burning a rough trip rather than a mighty tool for anyone performing at sub-threshold for a prolonged period of time. Should you want to obtain more information and deeper insight in the art of fat training don't hesitate to get back to me under: info@biomac.biz
Götz Heine

Joe Friel

Goetz--There's an old saying in science that may apply here... "In God we trust. All others must provide data."

Götz Heine

Hi Joe,
why don't you get yourself a volume and gas sensor the type available on the fitness market. Experiment with it and you will soon find out that what I state is valid. To prove what I state I do offer you a 10-day course you can do from home and you will see it works very well - like all my ideas and recommendations so far.
Your's in Sports physiology,

Joe Friel

Hi Goetz--I'm afraid my memory fails me. Could you please tell me again what it is you propose as far as diet? And, secondly, provide any data to support it. Thanks.

Götz Heine

Cream, whipped cream it is. I published the diet ín few words on my site. Like when we met in Phoenix in 2006 I do this diet once a year. Remember I didn't drink and had no food with me. During the diet my body fat drops below 10% and after a recovery of two weeks I start flying.
As a result of the Cream Diet an athlete stays notably longer in fat burning zone, produces significantly less lactic acid in comparison to before the diet, sweats less, his ketone production is close to if not at zero and his ability to exercise without getting hungry is increased. I stopped monitoring lab data as the process became so familiar but I can ask athletes who went on the diet recently whether they want to share insight in their improvements.

Jim Doyle

Hi Joe,
I read with interest your Blog and messages
from Götz.I recently competed in the Race around Ireland considered the 2nd toughest endurance Race in the world after RAAM. I was very kindly helped by Götz HEINE. I completed the Cream Diet and still trained with a reduced Volume of about 50 percent for about 10 days.I had a skin fold test done prior and about 2 weeks after the diet. Not that I need one as the mirror told me every thing I needed to know. I went from 12 percent down to 7 and a half percent body fat. I did a pre and post power test and no loss of power. I went on to compete in the RAI with using a diet of cheese,nuts, fruit,and dark chocolate. I have since had a full medical with blood tests and all is normal. I think this is enough evidence to support this theory. I also trained and raced using the mid cleat shoes that I bought from Götz.The Diet works try it for your self!

Jean Hubert

Hi Joe,
I read Gary Taubes' book and started following his dietary guidelines. We are training for a multi-stage endurance race (Cape Epic) with long hours in the saddle. My experience is that the body runs very well on fat provided you remain aerobic. I am amazed at how little one needs to eat and still remain strong and full of energy. It is obviously a complex issue with each of us reacting differently, but I would say it is worth trying going onto a low carb diet and trying to get your body to run on fat for long multi-stage events.

Joe Friel

Jean H--Yes, diet certainly has the potential to shift metabolic RER to a lower value for any sub-threshold intensity. Eating starch and sugar only at the right times is the key to this. I haven't read his bok but if that's what he's saying then we're on the same page. Good luck!

Mark Lorie Fitness

I would say that the relationship between VO2 max and fat-burning is the single most controllable, and therefore most important aspect, to any fitness program intended to assist with weight loss. My two cents....


Hi Joe,
Just wanted to write and say that I completed Gotz Heine's cream diet about 4 months ago. Since then my carb intake is absolutely minimal, I can go for 4 hour mountainous group rides with my mates and now win where I used to get a kicking. I consume considerably less water on rides, no carb drinks, bars or gels only fruit. My weight has gone from 79 kgs to 72.5 kg and bodyfat down from 18% to 8% . In short I have never felt belter on and off the bike. This may go against the common modern thinking of endurance athlete fueling however, for those of us who have now converted we know there exists other options.
Cheers and love the blog.

Brent Jaciow

Dear Joe,

I have been following a keto diet for over a year now with some refeeds after huge efforts, but on average my carb consumption is about 10% of total Kcal. I just got a BMR test and my R (RER) values averaged over 1.1. Have you ever seen this happen before? I can run a marathon after a 16hr fast with no food or intra-workout nutrition, go days without eating with little issue and maintain about 8% bodyfat. I am absolutely perplexed as to how this could happen without exercise. Any thoughts would be most appreciated!

Joe Friel

Brent Jaciow - That's very interesting. I've not seen any data on RER values and a keto diet.

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